Cigarette filters containing selective adsorbents



1965 A. w. SPEARS ETAL 3,217,719

CIGARETTE FILTERS CONTAINING SELECTIVE ADSORBENTS Filed April 16, 1962 POWDER FILTER FIBERS 3 TOBACCO 1 INVENTORS: ALEXANDER W.SPEARS WILLIAM E. ROUTH CHASE W. LASSITER JIMMY H. BELL QM MM THEIR ATTORNEYS United States Patent 3,217,719 CIGARETTE FILTERS CONTAINING SELECTIVE ADSORBENTS Alexander W. Spears, William E. Routh, Chase W. Lassiter, and Jimmy H. Bell, all of Greensboro, N.C., assignors to P. Lorillard Company, New York, N.Y., a corporation of New York Filed Apr. 16, 1962, Ser. No. 188,281 6 Claims. '(Cl. 131208) This invention relates to a new tobacco smoke filter which selectively removes certain products of combustion in tobacco smoke, and particularly to cigarette filters having a chemical complexing agent to selectively remove phenol and phenolic compounds in tobacco smoke.

According to the present invention, it has been found that a tobacco smoke filter containing a polymeric compound having the property of forming a complex with the phenol and phenolic compounds has a greatly improved efficiency for removing phenols and phenolic compounds from tobacco smoke.

Compounds which have been found to be particularly useful in this respect are polymers and copolymers of N- vinyl--methyl-2-oxazolidinone. In the copolymers, the active moiety is the oxazolidinone unit having the structural formula:

Hs Polymers or copolymers containing from 25 to 100% of the N-vinyl-5-methyl-2-oxazolidinoue unit have useful complexing activity. Monomers suitable for copolymerization with N-vinyl-S-methyl-Z-oxazolidinone include, but are not limited to, vinyl acetate. Other useful monomers would be those which contain the vinyl group (styrene, vinyl acetate, etc.).

The molecular weight of the complex-forming compounds is dependent on the specific material used. In selecting a suitable molecular weight, the vapor pressure of the complex-forming compound should be sufficiently low that it will remain in the filter during storage, and will not volatilize during the smoking of the cigarette. The vapor pressure of such complex-forming compounds should be from 0 mm. up to 40 mm. Hg at 25 0., however, the preferred range is between 0 mm. and 1 mm. Hg at 25 C.

According to the present invention, the complex-forming compounds are incorporated in a conventional tobacco smoke filter, usually made of cellulose or substituted cellulose fibers. However, the filter may be composed of natural fibers, mineral fibers and other synthetic fibers such as nylon, polypropylene and polyethylene. Mixtures of synthetic, mineral and natural fibers are also suitable. By manufacturing methods well known in the art, the fibers are formed into a compact plug having a plurality of tortu- 3,217,719 Patented Nov. 16, 1965 ice ticulate matter present in the tobacco smoke. The filter fiber provides support for the complex-forming compounds of the present invention, and accordingly no particular form or type of fiber material is required for the successful practice of this invention.

'A typical filter-cigarette is illustrated in FIG. 1. This comprises a plug of shredded tobacco 1 and, superimposed thereon, a tip comprising a plug of compact, fibrous base material 3. The filter tip and tobacco are joined in a unitary structure by a suitable wrapping paper 2. In the practice of the present invention, the fibrous base material 3 is impregnated with polymers or copolymers of N-vinyl- S-methyl-Z-oxazolidinone as described above. Depending on the method of impregnation, the selective adsorbents may form a thin film over the individual strands of fibrous material, or may be absorbed into the fibrous material, or as illustrated it may be in the form of a powder 4 supported by the fibrous base material 3.

The complex-forming compounds according to the present invention may be applied to the filter fibers before formation of the plug, and the amount of complex-forming compound may range from 0.01% to 100% by weight of the filter depending upon the manner in which the complex-forming compound is used. Some complexforming compounds may be incorporated into the filter as a solid powder. In that case, complex-forming compound is preferably present in an amount between 5% and 25% by weight of fiber. In other cases the complexforming compounds are more conveniently incorporated into the filter with the aid of a solvent, a compatible nontoxic plasticizer or both. Where the solvent technique is used, the complex-forming compound may be present in an amount between 0.01% and 25 by weight of fiber, the optimum range being between 0.3 and 2% by weight of fiber.

Suitable plasticizers are glyceryl triacetate, triethyl citrate, acetyl triethyl citrate and alkyl phthalates. The plasticizers should be present in amounts up to 20% by Weight.

In still another method the complex-forming compounds may be formed into a filter by fusion, sintering or other direct fabrication method. In such case, the entire filter plug is composed of the complex-forming compound.

Cigarette filters, according to the present invention, are illustrated by the following examples. As a basis of comparison, two types of filters using chemically inert mate rials are used as standards, namely a typical commercial filter of cellulose acetate and a filter comprised of cellulose acetate into which has been incorporated a powder which is inert with respect to phenol. The cigarettes were machine smoked and the products passing through the filter were collected and analyzed. The physical and filtration properties of these filters are given in Table 1. The selectivity of the cellulose acetate filter is probably due to an association complex between phenol and the oxygen atoms of the acetyl group.

The terms filter etficiency and phenol filter efficiency used in the following table and examples refer to the percentages of particulate matter and of phenol and ous passages to trap small diameter solid and liquid parphenolic compounds removed from the tobacco smoke.

TABLE 1 Total ggitration elective 1 Len th Plastieizer Filter Denier Total Plug Filtration ciency emova Fflter Matena mr n. Weight of Fiber Denier Draw Etficiency, of Phenol, of Phenol,

percent percent percent 1 19, 000 29 69. 0 61. 5 7 5 i fiitiltty iiu: 3 55, 000 .39 so. 0 54. 5 4. 5 Cellulose acetate 6% glyceryl triacet 6.. 3 2 55, 000 48 47. 0 71. 5 24. 5 Cellulose acetate and 15% do 3. 2 55, 000 36 56. 0 81. 5 25. 5

cellulose powder.

4 polyethylene fibers, said element containing a polymeric compound selected from the group consisting of polymers and copolymers containing the N-vinyl-5-methyl-2- oxazolidinone unit, said polymeric compound having a vapor pressure of mm. to 40 mm. Hg at 25 C.

3. A filter element for filter tip cigarettes according to TABLE 2.FILTERS CONTAINING POWDE RED COMPLEX-F0 RMING COMPOUND Complex-forming Wt. Per- Dcnier Total Length, Plug Total Filter Phenol Filter Compound cent on of Fiber Denier mm. Draw Efficiency, Elheieney,

Fiber Percent Percent 40 mesh poly [N-vinyl-- methyl-Z-oxazolidinone] 1 22 3. 2 55, 000 17 0. 43 49 84 Commercially available from the Dow Chemical Corporation under the trade name Devlex 130, and described in the Dow Chemical Corporation Technical Bulletin Devlex 130 issued August 1960. The polymer used has a molecular weight of about 150,000.

Example II A second method of incorporating the complex-forming compound into a cigarette filter is by use of a solvent technique. An exemplary solution consists of a copolymer of N-vinyl-S-methyl-2-oxazolidinone and vinyl acetate (in which the monomeric units are present in approximately equal mol ratios), ethanol and glycerol triacetate in the weight ratio 1:2:7, respectively. The solution of polymer, plasticizer and solvent was mixed with the cellulose acetatefibers at a concentration of 6% by weight. The filter fiber used had a denier of 3.2. Filter plugs were formed of the fibers. The filter plugs had a total denier of 55,000, a length of 17 mm., and a plug draw of 0.49. The total filter efficiency was 49% while the phenol filter efiiciency was 85.5%.

The copolymer used in this example is commercially available from the Dow Chemical Company under the trade name Devlex A515, and is described in Dow Chemical Corporation Bulletin, Devlex A515 issued August 1960.

The various filters set forth in the preceding examples have been described for exemplary purposes only, and it will be understood that the invention is not limited thereto except within the scope of the following claims.

We claim:

1. A filter element for filter tip cigarettes consisting essentially of a plug of a base material having a plurality of passages for trapping particulate matter in tobacco smoke and selected from the group consisting of cellulose, substituted cellulose, nylon, polypropylene and polyethylene fibers, said element containing a polymeric compound selected from the group consisting of polymers and copolymers containing the N-vinyl-S-methyl-Z- oxazolidinone unit. 7

2. A filter element .for filter tip cigarettes consisting essentially of a plug of a base material having a plurality of passages for trapping particulate matter in tobacco smoke and selected from the group consisting of cellulose, substituted cellulose, nylon, polypropylene and claim 2 wherein said polymeric compound has a vapor pressure of 0 mm. and 1 mm. Hg at 25 C.

4. A filter element for filter tip cigarettes consisting essentially of a plug of a base material having a plurality of passages for trapping particulate matter in tobacco smoke and selected from the group consisting of cellulose, substituted cellulose, nylon, polypropylene and polyethylene fibers, said element containing a polymeric compound selected from the group consisting of polymers and copolymers containing the N-vinyl-5-methyl-2- oxazolidinone unit, said polymeric compounds having a vapor pressure of 0 mm. to 40 mm. Hg at 25 C. and being present in an amount from 0.01% to by weight of said filter.

5. A filter element for filter tip cigarettes according to claim 4 wherein said polymeric compound is poly[N- vinyl-5-methyl-2 oxazolidinone] 6. A filter element for filter tip cigarettes according to claim 4 wherein said polymeric compound is a copolymer containing from 25% to 100% of the N-vinyl-5-methyl-2- oxazolidinone unit.

References Cited by the Examiner UNITED STATES PATENTS 2,707,959 3/1955 Shelanski 13110 2,839,065 6/1958 Milton 13110 2,902,998 9/ 1959 Durandeau 131-9 2,933,460 4/1960 Richter et al 131--10 2,941,906 6/1960 Haden 13 l-17 2,941,907 6/1960 Tousignant et a1. 13117 2,946,772 7/ 1960 Walles et al 260-88.3 2,946,773 7/1960 Walles et al 260-883 2,948,656 8/1960 Tousignant et a1. 26088.3

FOREIGN PATENTS 760,772 11/ 1956 Great Britain.

ABRAHAM G. STONE, Primary Examiner. MELVIN D. REIN, Examiner. 

1. A FILTER ELEMENT FOR FILTER TIP CIGARETTES CONSISTING ESSENTIALLY OF A PLUG OF A BASE MATERIAL HAVING A PLURALITY OF PASSAGES FOR TRAPPING PARTICULATE MATTER IN TOBACCO SMOKE AND SELECTED FROM THE GROUP CONSISTING OF CELLULOSE, SUBSTITUTED CELLULOSE, NYLON, POLYPROPYLENE AND POLYETHYLENE FIBERS, SAID ELEMENT CONTAINING A POLYMERIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF POLYMERS AND COPOLYMERS CONTAINING THE N-VINYL-5-METHYL-2OXAZOLIDINONE UNIT. 